AWG Wire Gauge Chart with mm² and Voltage Drop

The zeros: 0000, 000, 00 and 0

Wire thicker than 1 AWG continues with 0, 00, 000 and 0000. These are said "one-aught" to "four-aught" and written 1/0, 2/0, 3/0 and 4/0. The chart lists both spellings, so 0000 and 4/0 are the same wire, 11.68 mm across with a cross-section of 107.2 mm². Beyond 4/0 the size is given directly as an area in kcmil (thousands of circular mils), where 1 kcmil is 0.5067 mm². Older documents call the same unit MCM.

AWG, mm² and SWG are different things

• AWG describes a diameter step. Metric cable sizes, for example in IEC 60228, describe the conductor cross-section in mm² and use round numbers such as 1.5, 2.5, 4 and 6. The two lists do not line up, which is why the AWG to mm² chart shows the closest metric size and how far off it is. 13 AWG is 2.624 mm², close to a 2.5 mm² cable. 10 AWG is 5.261 mm², which sits between 4 and 6 mm².
• SWG, the British Standard Wire Gauge, is another backwards-counting scale, but its steps are different. A wire called 12 SWG is about 2.64 mm across while 12 AWG is 2.053 mm, so never swap one for the other.

Resistance and voltage drop

• The resistance columns use annealed copper at 20 °C, which is 100% IACS or 58.0 MS/m, giving a resistivity of 1.724 × 10⁻⁸ ohm metre. Resistance per length is that resistivity divided by the cross-section area, which is why a thicker wire has a lower resistance: 10 AWG is 3.277 ohm per km, 20 AWG is 33.31 ohm per km. Aluminium at 61% IACS has about 1.64 times the resistance of copper for the same size.
• Voltage drop for a two-wire DC or single-phase circuit is V = I × R × 2L, with L the one-way length because the current also returns. For 15 A over 50 ft of 12 AWG copper, R is 1.588 ohm per 1000 ft times 100 ft, which is 0.159 ohm, so the drop is 2.38 V, or 1.99% of a 120 V supply. This only counts resistance. Temperature, AC reactance and connectors change the result.

Solid wire, stranded wire and how to choose a size

• The AWG number of stranded wire is based on the total copper area of all strands, so a stranded 12 AWG wire has about the same copper as a solid 12 AWG wire. Its overall diameter is a little larger because of the gaps between strands, and it is more flexible, which is why it is used for leads and anything that moves.
• This chart deliberately has no current ratings. How much current a wire may carry depends on the insulation temperature rating, how it is installed, the ambient temperature, how many conductors share a conduit and the rules that apply where you live. Use the NEC or your local code and ask a qualified electrician for anything in a building. What this page gives you is the geometry and resistance, so you can compare sizes, convert to metric and check that voltage drop stays acceptable.

Where the numbers come from

Every value is computed in your browser from the ASTM B258 definition, d = 0.005 in × 92^((36 − n) / 39), not copied from a table, and then compared with the American wire gauge article on Wikipedia. Diameters are shown to four significant figures. Metric sizes are a selection of IEC 60228 nominal cross-sections. Checked October 2026.